Aortic aneurysm and aortic dissection are relatively dangerous vascular diseases that are commonly found clinically, and without duly treatment they might endanger the patient's life because of aortic rupture; traditional methods of surgical operation have low success rate of cure, and high risks.
Interventional therapy of aortic aneurysm and aortic dissection is a new piece of technology applied clinically in recent years. Its principle is that a length of stent-graft with suitable dimension is preloaded into a delivery and release device, then guided into the human body, and under surveillance of X-ray monitoring equipment, the stent-graft is released at the diseased region of the aorta and conformed tightly onto the aortic vessel wall, so as to block the blood acquiring channel of the diseased region and to gradually form thrombus at the diseased region of the aorta, thereby the risk of massive hemorrhage caused by aortic rupture is eliminated, and the therapeutic purpose is achieved.
In prior art, the patent CN2548564Y disclosed a delivery and release device for abdominal aorta stent-graft, which comprises a mandrel and a sleeve, wherein, the mandrel comprises a guiding head at the front and an inner tube connected on the rear side of the guiding head for the stent-graft to be sheathed thereon, the mandrel also comprises a slidable pushrod and a central tube, and a through hole extending axially through the mandrel is formed in the center of the mandrel; the sleeve is a hollow structure and integrally sleeves on the mandrel at the rear side of the guiding head, the front part of the sleeve is an outer sheath tube, the rear part of the sleeve is a connecting base with a liquid injection port, the outer sheath tube is slidably coordinating with the pushrod in the axial direction, and a space for placing the stent-graft is formed between the inner tube and the outer sheath tube; a rotatable shaft is provided inside the sleeve, the rotatable shaft is supported on the guiding head by a rotation fulcrum, a controlling suture is provided on the rotatable shaft, one end of the suture is wound around the rotatable shaft, the other end of the suture passes through the stent-graft and is tightened, during usage, by rotating the rotatable shaft to release the controlling suture, the front end of the stent-graft is released.
In the above-mentioned technical solution, because the length-diameter ratio of the rotatable shaft for releasing the controlling suture to release the stent-graft is relatively large, when rotating the handle at the tail end of the rotatable shaft to control the shaft, the torque is not able to be effectively transmitted, which leads to difficulty in the operation of releasing the stent-graft; also, when rotating the rotatable shaft to release the stent-graft, it is possible for the already positioned stent-graft delivery and release device to shift its position, thus cause the position of the stent-graft to shift, which leads to inaccuracy of the release position of the stent-graft; furthermore, when releasing the stent-graft, it is required to rotate the rotatable shaft in order to release the controlling suture to allow the suture to stretch, however, there is a lot of uncertainty in the winding manner of the controlling suture, and possible problems of knotting or crossing of the controlling suture might cause the controlling suture to be not able to stretch, which leads to failure in releasing the stent-graft.
As an alternative solution to the problem in the above-mentioned technology of difficulty in releasing the stent-graft, U.S. Patent US2009099637A1 discloses a delivery and release device for stent-graft, a guiding head of this device is connected to and internally communicated with a central tube at the rear side, an outer tube sleeves on the central tube at the rear side of the guiding head, a larger end of the guiding head is provided with metal bars fixed thereon in the axial direction, a locking member is arranged close to the guiding head and sheathed between the outer tube and the central tube, the locking member is provided with a through hole to form a detachable connection with the metal bars, a positioning tube is sheathed between the locking member and the central tube and passes through the locking member; when loading the device, the stent-graft is tightened and sheathed between the positioning tube and the central tube, and the metal bars are guided through projecting loops at the proximal end (the end proximal to the heart) of the stent-graft and then inserted into the through hole so as to fasten the stent-graft, and when using the device, the outer tube is first pulled backwards to release the rear part of the stent-graft, and then the central tube is pushed forwards to drive the metal bars on the guiding head to move forwards and detach from the locking member, thereby completely releasing the stent-graft. In this technology, the way of releasing the stent-graft by using a central tube to drive metal bars on a guiding head to detach from a through hole in a locking member so as to separate the metal bars from the locking member and the projecting loops at the proximal end of the stent-graft is simple to operate and easy to implement, and solves the problems in the above-mentioned technology such as difficulty in the operation of releasing the stent-graft, inaccuracy of the release position and low success rate of release; however, in this technology, rigid metal bars are utilized to pass through the projecting loops at the proximal end of the stent-graft and then be inserted into the locking member so as to be fastened, as the volume of the stent-graft is very small and the projecting loops at its proximal end are also very small, the metal bars need to be machined into a size small enough to pass through the projecting loops of the stent-graft, which puts high requirements on precision of machining and thus increases the cost, and also as the material used for producing the stent-graft is low in hardness, the rigid metal bars passing through the projecting loops of the stent-graft might easily cause permanent deformation of the proximal end of the stent-graft, and when released into a human body for utilization, the deformed stent-graft might not be conformed to the blood vessel firmly at the deformed part, as a result, blood leakage occurs, and more catastrophically, the stent-graft does not function as expected and the operation becomes a failure.